Forming means for profile grinding wheels



' April 8, 1952 c. B. A. PORTER 2,591,954

FORMING MEANS FOR PROFILE GRINDING WHEELS Filed May 2', 1949 2 SHEETS-SHEET 1 l4 ,9 ,2 l 24 m x 22 I 7 23 F /1/ r17 .20 don 2/ A ril 8, 1952 c. B. A. PORTER I 2,591,964 E FORMING MEANS FOR PROFILE GRINDING WHEELS Filed May 2, 1949 2 SHEETS-SHEET 2 PM or Patented Apr. 8, 1952 FORMING MEANS FOR PROFILE GRINDING WHEELS Charles Benjamin Albert Porter, Preston, Yeovil, England, assignor to Harold Stuart Hallewell, Hayes, Middlesex, England Application May 2, 1949,.Serial No. 90,952 In Great Britain May 3, 1948 4 Claims. (Cl. 125-11)' This-- invention relates to apparatus for usein forming on a' grinding wheel a profile which is the complement of a'profile required to'be-g-round thereby on a tool, die, gauge or other Workpiece; by means of a dressing-tool point operated by a pantog'raph mechanism having a 01- lowermember adapted to follow atemplate. The apparatus to which: the invention relates is able to form profiles" havingportions which are radial with respect to the axis of rotation of the'grin'din'g wheel and which face both right andleft; and this ability is provided by arranging for the holder for the dressing tool to rock about an axis which is tangential to" the grinding wheel,v and for the template-follower member to rock about an axis which is: perpendicular to the plane of the template, a linkage supplementary to the pantograph mechanism being provided whereby the dressing-tool holder is constrained to' rock in unison with the making of the template-follower member.- Apparatus of this kind is described in patent application Serial No. 567,398 of C. B. A. Porter and C. P. Seymour filed December 9. 1944 (Patent No. 2,469,844).

The dressing toolconsists of a hard tip, e. g. a diamond, mounted on a wedge-section or conical end of a cylindrical shank, and, in order to avoid risk of cutting of the shoulder of the dressing tool by salient parts of the profile of of the grinding wheel, the template-follower member is fitted with a sector-shaped or equivalent guard element having an apex angle not less than that of the dressing tool. This guard element co-operates with the template so as to prevent any part of the dressing tool other than its tip from touching the grinding wheel.

The dressing tool usually has a radiused tip, and the template-follower member has aworking tip which is geometrically similar in section to the section of the tip of the dressing tool, the ratio of the radii of these two tips being equal to the mechanical advantage of the pantograph mechanism. The centre about which the radiused tip of the template-follower member is formed is onthe rocking axis of this member, and the centre about which the radiused tip of the dressing tool is formed is on the rocking axis of the dressing-tool holder.

It is convenient to make the working tip of the template-follower member a cylindrical tip on a; pin det'achably' fitted to this member, so that it can be readily changed as required to suit dressing tools having tips of difi'erent' radii.

The object of this invention is to provide means whereby the above-mentioned guard element can be conveniently matched to different dressing tools.

A preferred arrangement of template-follower member and guard means in accordance with the invention, as applied to apparatus of the design shown diagrammatically in Figure l of the above-mentioned patent specification, will be described with reference to the accompanying drawings, in which:

Figure 1 is an elevation of the template-follower member and its bearing in the top end of an arm of the pantograph mechanism, the figure being a section on the line ll in Figure 2.

Figure 2 is an elevation of the same parts as viewed from the left-hand side of Figure 1.

Figure 3 is a sectional plan on the line 3'-3 in Figure 2.

Figure 4 is a perspective diagrammatic view of the complete pantograph apparatus, suitable for use with a surface grinder of conventional type.

The apparatus shown in Fig. 4 includes a rectangular base plate 4| engaged by the magnetic chuck 42 of the surface grinder and has a depending flange 43 at one edge, which serves to locate the base square with respect to the grinder. A bracket 44 rigid with the base carries a board 45 to which is fixed a template 46 lying in a vertical plane parallel to the axisof the grinding wheel 41. The pantograph'linkage includes a more or less horizontal long link 48 pivoted on a bearing pin 49 mounted onthe base 4! and disposed perpendicularly to the tern-- plate. A short more or less vertical link 50 is also pivoted on the pin 49. An arm l3 parallel to the link 5|] is pivoted to the free end of the link 48 and carries a template-follower 23 at its upper end. A second arm 5| parallel to the link 48 is connected between the upper end of the link 50 and a point on the template-follower arm l3. The arm 5| carries a wheel-dressing tool 52. r

The template-follower 23 is formed by a horizontal pin projecting coaxially from a shaft H) which is journalled in the upper end of the arm I3. To the end of the pin 23 is fitted the above mentioned guard element shown diagrammatically and denoted by 36, 31.

The dressing tool is carried by a horizontal shaft 53 journalled in the arm 5|, the arrangement being such that the diamond tool 52 can beset below the wheel 41.

The template-follower pin 23 and the diamond-holder shaft 53 are connected for rocking in unison under control of a hand wheel H on the shaft in. The necessary connection consists of a steel belt 54 on pulleys 55 and 56 respectively fixed on the shaft 53 and rotatable on a pivot pin 5! connecting the arms 5| and I3, and a steel belt I8 on pulleys 58 and 20 respectively fixed to the pulley 55 and the shaft Ill. The belts are pinned to the respective pulleys, by means hereinafter described, so as to prevent slip.

Figures 1 to 3 show actual preferred constructional forms of certain parts that are shown merely diagrammatically in Figure 4. As is evident from Figs. 1 to 3, the shaft In of the template-follower member is hollow and is mounted in ball bearings H in a housing on the upper end of a tubular arm |3 of the pantograph mechanism, which end is movable in directions in a plane perpendicular both to the plane of Figure l and also to the shaft ID. A knob I4 operable both for moving the follower along the edge of the template and also for rocking the shaft I is fixed by a screw I5 to a bearing clamp nut I6 which is engaged with a threaded end portion of the shaft I0 and secured by a lock-nut H. A flexible steel belt I8 is pinned at I9 to the pulley 20 which is fixed by a screw 2| to the shaft ID. These means are mechanically equivalent to the supplementary linkage shown in Figure l of the said patent specification.

The template-follower pin 22 having a cylindrical working tip 23 is detachably held in a socket 24 in the shaft l0, co-axially with this shaft, by a draw bolt 25 passing through the shaft and tensioned by a nut 26.

An angle bracket 21 is fixed to the end of the rocking shaft [0 of the template-follower member in such a manner that one limb 28 of the bracket extends parallel to and alongside the follower pin 22. The limb 28 has a rectangular channel-section guide way 29 which runs parallel to the template and which opens towards the template. Two bars 30 and 3| are placed parallel to each other in the guide way 29, the bar 30 being at the mouth and the bar 3| at the bottom of the channel section. These bars are an accurate sliding fit between the top and bottom side walls of the guide way, and their sides that face each other are stepped to form ledges 32 and 33 (Figure 3) supporting a rectangular nut 34 which can be clamped down onto the ledges by a clamping screw 35, whereby the bars 3|] and 3| can be locked in any desired positions of their sliding adjustment. Two wings 36 and 31 of fiat sheet metal and lying in the plane of the template are fixed to the opposite ends of the bars respectively. The wing 36 is fixed directly to the bar 30 by screws 38, and the wing 31 is fixed to the bar 3| by screws 39 passing through a distance block 40.

This arangement enables the wings to be easily set to positions in which their working edges are tangential to a follower tip 23 of any diameter within limits. It also enables the wings and bars to be easily replaced by other wings and bars providing a different apex angle.

The apex angle between the Working edges of the guard wings is not less than the apex angle of the tapered nose of the dressing tool. Consequently, when the follower tip 23 is used having a radius appropriate to the radius of the tip of the dressing tool, as the follower member and dressing-tool holder are rocked in unison |2 formed 4 by the handle l4 in order to introduce the dressing tool tip into re-entrant portions of the profile of the grinding wheel, which face different directions, the guard wings will cooperate with the working edge of the template so as to prevent excessive angular displacement of the handle such as would cause salient portions of the profile of the grinding wheel to cut into the nose of the dressing tool.

I claim:

1. Apparatus for dressing a grinding wheel and including a base, a template-holder on said base, a pantograph mechanism comprising a parallelogram of arms pivotally mounted on said base for movement parallel to the templatecontaining plane of the template-holder, a template-follower member pivotally mounted on a first of said arms for rocking with respect to said first arm about an axis perpendicular to said plane, a dressing-tool holder pivotally mounted on a. second of said arms for rocking with respect to said second arm about an axis perpendicular to said plane, a dressing-tool having a shank and a tapered nose with a radiused tip, said dressing-tool being mounted on said holder with its shank substantially perpendicular to the holder axis, and means interconnecting the template-follower member and the holder for constraining them to rock in unison, thetemplate-follower member having a. detachable cylindrical tip coaxial with the templatefollower pivot, and a guard element constituted by two wings having respectively two working edges lying in the template-containing plane of the template holder substantially tangentially to said tip and inclined to each other at a fixed apex angle, and said wings being mounted on the template-follower member by means enabling them both to be bodily displaced towards and away from each other in a direction perpendicular to the rocking axis of the templatefollower member and perpendicular to a line bisecting the apex angle and also to be locked in various positions of adjustment.

2. Apparatus as claimed in claim 1, wherein the means for adjustably mounting the guard wings include a rectangular channel-section guide way rigid with the template-follower member and disposed parallel to and opening towards the template, two bars slidably fitted in said guide way parallel to each other and respectively carrying the two wings, a clamping member engaging said bars, and a clamping screw passing through the wall of said guide way and cooperating with said clamping member.

3. Apparatus for dressing a grinding wheel and including a base, a template-holder on said base, a pantograph mechanism mounted on said base, a template follower member pivotally mounted on a first arm of said pantograph mechanism for rocking with respect to said first arm about an axis perpendicular to the template-containing plane of the template holder, a dressing-tool holder pivotally mounted on a second arm of said pantograph mechanism for rocking with respect to said second arm about an axis perpendicular to said plane, said pantograph mechanism connecting together for movement parallel to said plane said template follower member and said dressing tool holder, a dressing-tool having a shank and a tapered nose with a radiused tip, said dressing-tool being mounted on said holder with its shank substantially perpendicular to the holder axis. and means interconnecting the template-follower member and the holder for constraining them to rock in unison, the template-follower member havin'gf'a detachable cylindrical tip coaxial with the template-follower pivot, and a guard element 'constituted by two wings having respectively two working edges lying in the template containing plane of the template holder substantially tangentially to said tip and inclined to each other at a fixed apex angle, and said wings being mounted on the template-follower member by means enabling them both to be bodily displaced towards and away from each other in a direction perpendicular to the rocking axis of the template-follower member and perpendicular to a line bisecting the apex angle and also to be locked in various positions of adjustment.

4. Apparatus as claimed in claim 3, wherein the means for adjustably mounting the guard wings include a rectangular channel-section guide way rigid with the template-follower member and disposed parallel to and opening towards the template, two bars slidably fitted in said guide way parallel to each other and respectively carrying the two Wings, a clamping member engaging said bars, and a clamping screw passing through the wall of said guide way and co-operating with said clamping member.

CHARLES BENJAMIN ALBERT PORTER.

REFERENCES CITED UNITED STATES PATENTS Name Date Hanson June 1, 1920 Number 

